Effect of Thermophilic Nitrate Reduction on Sulfide Production in High Temperature Oil Reservoir Samples

Okpala, Gloria N.; Chen, Chuan; Fida, Tekle Tafese; Voordouw, Gerrit

doi:10.3389/fmicb.2017.01573

Cited by 40 publications

(25 citation statements)

References 61 publications

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“…Nitrate has been used as a biological treatment in oil reservoir systems since the 1990s ( Coates et al, 1993 ; Hubert et al, 2003 ; Arensdorf et al, 2009 ; Gieg et al, 2011 ). This treatment has direct and indirect effects on sulfate reduction but is not always predictable ( Hubert and Voordouw, 2007 ; Voordouw et al, 2009 ; Gieg et al, 2011 ; Carlson et al, 2015a ; An et al, 2017 ; Okpala et al, 2017 ; Suri et al, 2017 ; Engelbrektson et al, 2018 ). Nitrate has multiple mechanisms of action to control sulfate reduction.…”

Section: Introductionmentioning

confidence: 99%

Mitigating Sulfidogenesis With Simultaneous Perchlorate and Nitrate Treatments

et al. 2018

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Sulfide biogenesis (souring) in oil reservoirs is an extensive and costly problem. Nitrate is currently used as a souring inhibitor but often requires high concentrations and yields inconsistent results. Recently, perchlorate has displayed promise as a more potent inhibitor in lab scale studies. However, combining the two treatments to determine synergy and effectiveness in a dynamic system has never been tested. Nitrate inhibits perchlorate consumption by perchlorate reducing bacteria, suggesting that the combined treatment may allow deeper penetration of the perchlorate into the reservoir matrix. Furthermore, the metabolic intermediates of perchlorate and nitrate reduction (nitrite and chlorite, respectively) are synergistic with the primary electron acceptors for inhibition of sulfate reduction. To assess the possible synergies between nitrate and perchlorate treatments, triplicate glass columns packed with pre-soured marine sediment were flushed with media containing sulfate and an inhibitor treatment [(i) perchlorate; (ii) nitrate; (iii) perchlorate and nitrate; or (iv) none]. Internal geochemistry and microbial community changes were monitored along the length of the columns during six phases of increasing treatment concentrations. In a final phase all treatments were removed. Sulfide production decreased in all treated columns in conjunction with increased inhibitor concentrations relative to the untreated control. Interestingly, the potency of the “mixed” treatment was additive relative to the individual treatments suggesting no interaction. Microbial community analyses indicated community shifts and clustering by treatment. The mixed treatment column community’s trajectory closely resembled that of the community found in the perchlorate only treatment, suggesting that perchlorate was the dominant control on the “mixed” community structure. In contrast, the nitrate and untreated column communities had unique trajectories. This study indicates that concurrent nitrate and perchlorate treatment is not more effective than perchlorate treatment alone but is more effective than nitrate treatment. As such, treatment decisions may be based on economic factors.

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Section: Introductionmentioning

confidence: 99%

Mitigating Sulfidogenesis With Simultaneous Perchlorate and Nitrate Treatments

et al. 2018

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“…Oil fields harboring organisms that reduce nitrate to ammonia are potentially amenable to souring control being achieved with addition of less nitrate, as DNRA is an 8 mol electron transfer reaction per mole of nitrate while denitrification of nitrate to N 2 is a 5 mol electron transfer reaction per mole of nitrate (Table 1 , R5 vs. R3). The lower cost to companies of using less nitrate may be attractive to operators, but this would depend on a knowledge of the ecophysiology of the NRB community present in a given oil production system, e.g., NRB metabolism and whether nitrate gets converted to fully reduced end products (Reinsel et al, 1996 ; Fida et al, 2016 ; Okpala et al, 2017 ).…”

Section: Resultsmentioning

confidence: 99%

Using Thermodynamics to Predict the Outcomes of Nitrate-Based Oil Reservoir Souring Control Interventions

Dolfing

Hubert

2017

Front. Microbiol.

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Souring is the undesirable production of hydrogen sulfide (H2S) in oil reservoirs by sulfate-reducing bacteria (SRB). Souring is a common problem during secondary oil recovery via water flooding, especially when seawater with its high sulfate concentration is introduced. Nitrate injection into these oil reservoirs can prevent and remediate souring by stimulating nitrate-reducing bacteria (NRB). Two conceptually different mechanisms for NRB-facilitated souring control have been proposed: nitrate-sulfate competition for electron donors (oil-derived organics or H2) and nitrate driven sulfide oxidation. Thermodynamics can facilitate predictions about which nitrate-driven mechanism is most likely to occur in different scenarios. From a thermodynamic perspective the question “Which reaction yields more energy, nitrate driven oxidation of sulfide or nitrate driven oxidation of organic compounds?” can be rephrased as: “Is acetate driven sulfate reduction to sulfide exergonic or endergonic?” Our analysis indicates that under conditions encountered in oil fields, sulfate driven oxidation of acetate (or other SRB organic electron donors) is always more favorable than sulfide oxidation to sulfate. That predicts that organotrophic NRB that oxidize acetate would outcompete lithotrophic NRB that oxidize sulfide. However, sulfide oxidation to elemental sulfur is different. At low acetate HS− oxidation is more favorable than acetate oxidation. Incomplete oxidation of sulfide to S0 is likely to occur when nitrate levels are low, and is favored by low temperatures; conditions that can be encountered at oil field above-ground facilities where intermediate sulfur compounds like S0 may cause corrosion. These findings have implications for reservoir management strategies and for assessing the success and progress of nitrate-based souring control strategies and the attendant risks of corrosion associated with souring and nitrate injection.

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“…Aliquots (20 mL) of anaerobic CSBK medium in 60 mL serum bottles were amended with 1 mL of MHGC oil (O) and either 5 mM sulfate (S), 5 mM sulfate and 10 mM nitrate (SN), 5 mM sulfate and 10 mM perchlorate (SP), 5 mM sulfate and 10 mM nitrate and 10 mM perchlorate (SNP), or 10 mM perchlorate (P). Bottles were inoculated with 1 mL of 18PW, concentrated 20-fold by centrifugation ( Okpala et al, 2017 ). Sterile controls, containing 20 mL of CSBK medium, 1 mL of MHGC oil and electron acceptors, but no inoculum, were also prepared.…”

Section: Methodsmentioning

confidence: 99%

Comparison of Nitrate and Perchlorate in Controlling Sulfidogenesis in Heavy Oil-Containing Bioreactors

Okpala

Voordouw

2018

Front. Microbiol.

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Control of microbial reduction of sulfate to sulfide in oil reservoirs (a process referred to as souring) with nitrate has been researched extensively. Nitrate is reduced to nitrite, which is a strong inhibitor of sulfate-reducing bacteria (SRB). Perchlorate has been proposed as an alternative souring control agent. It is reduced to chlorate (ClO3-) and chlorite (ClO2-), which is dismutated to chloride and O2. These can react with sulfide to form sulfur. Chlorite is also highly biocidal. Here we compared the effectiveness of perchlorate and nitrate in inhibiting SRB activity in medium containing heavy oil from the Medicine Hat Glauconitic C (MHGC) field, which has a low reservoir temperature and is injected with nitrate to control souring. Using acetate, propionate and butyrate as electron donors, perchlorate-reducing bacteria (PRB) were obtained in enrichment culture and perchlorate-reducing Magnetospirillum spp. were isolated from MHGC produced waters. In batch experiments with MHGC oil as the electron donor, nitrate was reduced to nitrite and inhibited sulfate reduction. However, perchlorate was not reduced and did not inhibit sulfate reduction in these incubations. Bioreactor experiments were conducted with sand-packed glass columns, containing MHGC oil and inoculated with an oil-grown mesophilic SRB enrichment. Once active souring (reduction of 2 mM sulfate to sulfide) was observed, these were treated with nitrate and/or perchlorate. As in the batch experiments, 4 mM nitrate completely inhibited sulfide production, while partial inhibition occurred with 1 and 2 mM nitrate, but injection of 4 mM perchlorate did not inhibit sulfate reduction and perchlorate was not reduced. The enriched and isolated PRB were unable to use heavy oil components, like alkylbenzenes, which were readily used by nitrate-reducing bacteria. Hence perchlorate, injected into a low temperature heavy oil reservoir like the MHGC, may not be reduced to toxic intermediates making nitrate a preferable souring control agent.

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Effect of Thermophilic Nitrate Reduction on Sulfide Production in High Temperature Oil Reservoir Samples

Cited by 40 publications

References 61 publications

Mitigating Sulfidogenesis With Simultaneous Perchlorate and Nitrate Treatments

Mitigating Sulfidogenesis With Simultaneous Perchlorate and Nitrate Treatments

Using Thermodynamics to Predict the Outcomes of Nitrate-Based Oil Reservoir Souring Control Interventions

Comparison of Nitrate and Perchlorate in Controlling Sulfidogenesis in Heavy Oil-Containing Bioreactors

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